Slightly passive-aggressive maybe, but an asshole? not so much. Granted that what I said is more to the effect of ridding yourself of said person easily as opposed to putting up with him or direct conflict. No need for name calling(as indirect as it may have been). if you have a problem with my suggestion, you can argue that without the attempt to blatantly attach a negative stigma to everything I have to say from here on out.
That sucks.. He's obviously extremely immature.. I want to say that the people saying "don't be his friend" are wrong and that is a lot harder than it sounds, but really that's the only option other than just accepting it and hanging out less, so that when you deal with it, it isn't as annoying. As for stopping being his friend-- if you so choose-- just slow down hanging out, hang out less and less, and eventually stop all together.
Sorry not trying to call you a asshole, but doing something like that for the sake of ease seems to be a rather asshole way of doing it. Slightly passive aggressive is a understatement though It's happened to me and it's not a good feeling at all when a friend doesn't have the guts to spit up that they don't want to be friends anymore. Sometimes it feels like they weren't your friend at all.
Eh, I've had it done to me and I've had to do it. personally I find it much easier and less offensive. to each their own though.